To be clear, your source water is 7pH, 6dkH, and after putting it into the tank at various concentrations, you measure the tank at 8.4pH, 2-3kH.
1. I would take some gravel and put it into a small glass of RO and see where it settles. 2. I would do the same with any rocks (and any petrified wood ;~) Alternately drip some pH Down on the stones and note their reaction. A fizzing would indicate they are releasing calcium into the water. Note that iirc, some stones can release kH and not gH, Nevada Ice (or something like that). 3. Accordingly, measure the dgH in controlled conditions to see what it's doing (contributing?). 4. Outside my expertise, but there are different buffering compounds, which results in a few natural pH balancing points (ie: 7.2-7.4 is common, as is 7.6 and 8.2 and 8.4. You typically don't find water at 7.1, 7.3 or 7.9pH. If buffer type A was propping you up to 7.0, and it was consumed by the plants and replaced by buffer type B, you might balance at a different pH. Bit of a long shot, but remineralizations can be less stable than expected. 5. Another long shot, pH is a function of CO2 and kH. Is it possible that there is a higher concentration of CO2 in the barrel causing the pH to measure low? Easy to verify. Take a glass of your perfect water and let it sit on the counter overnight before measuring again. You need to establish some baseline measurements. Are you causing the CO2 levels in the tank to elevate/decrease? Time of day will also affect your pH results in a tank with live plants due to photosythesis. That's all I got off the top of my head, some dumb and some not so dumb ideas. You have to figure out which are which ;~) hth NetMax On Feb 1, 6:46 pm, NitroCarbon <[email protected]> wrote: > *All water hardness parameters will be referred to in German degrees > (dGH and dKH)... > > Group! > > I've come up against a strange situation with my water throughout the > last several weeks (refer to my previous list postings about reverse > osmosis to get more context). > > Indeed, throughout the battle waged against the local water supply, for > my biggest tank I've come up against a situation I can't explain, or > correct for that matter... > > _The short version:_ > ammonia: 0 > nitrates: ~15ppm > nitrite: 0 > GH: 12 (easily controlled upward or downward) > *pH: 8.4 > kH: 2 to 3* > > _The Long version:_ > I can't understand that. With a pH that high, the KH should be high, > right? Wouldn't that be what you'd expect? Right out of the 55 gallon > drum collection barrel I put the fresh RO water into 5 gallon jugs and > treat the water with buffers and remineralize it, mix it all up, and let > it be for about 5 days. At that point I measure it and pH is at a > perfect 7, KH is 6, GH is dependent on how much remineralizing additive > I've used. > > I had been doing semi-weekly 20% water changes with this "purefect" > water for about 2 weeks give or take. It added up to about 4 water > changes. The high pH<=>low KH condition persisted *in* the tank after > the tank water was tested. > > Finally I decided I'd risk a 60% water change using the "purefect" water > source. I reasoned that the fish had been exposed sufficiently to the > new water that the change would be minimal, and I performed the change > over a 4 hour period. Then I waited... for 2 hours, and tested the tank > water. pH was 7.1, kH was 3, and GH was 12 (I'm going to be reducing > that slowly downward into the discus-friendly range). > > Finally I waited until the next afternoon and tested the water again. > pH was 7.4 and kH was 2. GAAAA! At this point I started getting > concerned about pH crashes and poised some questions to the group and at > other online places of aquatic community. My responses here on TFA > FARRR outshined the horrifically-transparent anecdotal BS. I was > comforted by what I learned in the thread because my tank is heavily > planted. I also took heart because the tank remains at a steady kH of 2 > now. > > _The Conclusion:_ > I desire more KH and a lower pH. What I'm seeing is not what I expected. > > _The Questions:_ > What could explain this situation, and how could I attain my goal of pH > 7, KH 6? > > ~nc
